Switch-style checkbox variables missing in documentation

Created by: xorinzor

Prerequisites

• I have searched for duplicate or closed issues
• I have validated any HTML to avoid common problems
• I have read the contributing guidelines

Describe the issue

The documentation lists the sass variables for the checkboxes, but the switch-style variables are missing.

Reduced test cases

N/A

What operating system(s) are you seeing the problem on?

Windows, macOS, Android, iOS, Linux

What browser(s) are you seeing the problem on?

Chrome, Safari, Firefox, Microsoft Edge, Opera

What version of Bootstrap are you using?

N/A